Positive electrode material and preparation method and use therefor, lithium-ion battery positive electrode pole piece, and lithium-ion battery

ABSTRACT

The present disclosure relates to the technical field of secondary battery, and discloses a positive electrode material and a preparation method and use therefor, a lithium-ion battery positive electrode poly piece, and a lithium-ion battery.

CROSS REFERENCE TO RELATED APPLICATIONS

The application claims priority to Chinese Application No.202110736089.8, filed on Jun. 30, 2021, entitled “CATHODE MATERIAL,PREPARATION METHOD AND USE THEREOF, CATHODE ELECTRODE OF LITHIUM IONBATTERY, AND LITHIUM ION BATTERY”, the content of which is incorporatedherein by reference.

FIELD

The present disclosure relates to the technical field of secondarybattery, in particular to a cathode material, a preparation method and ause thereof, a cathode electrode of lithium ion battery, and a lithiumion battery.

BACKGROUND

With the rapid development of the electric vehicle industry, the cathodematerial of lithium ion battery with a high energy density and a longservice life have attracted great attention. The layered ternarymaterials (Nickel-Cobalt-Manganese, or NCM) have a relatively highcapacity and exhibit great potential for development. However, when thecontent of nickel in NCM increases, the stability of said materialgradually decreases. The highly active ions Ni⁴⁺ generated during thecharging process will react with an electrolyte to form NiO like rocksalt phases, which severely damage the structure of said layeredmaterial, result in collapse of the cathode structure, thereby inducingthe dissolution of transition metal ions, phase transformation andprecipitation of lattice oxygen. The “secondary particles” ofconventional multicrystal NCM at present are generally composed of manynanometer-scale “primary particles”, and the changes of latticeparameters will lead to the formation of micro-cracks during thecharging and discharging process. The formed micro-cracks may exposefresh interfaces inside the particles, further accelerating thestructural attenuation. It shall be noted that the higher is the nickelcontent, the more pronounced is the destructive effect of the cracks. Tosum up, a major cause of the reduced cycle life of NCM, especially NCMwith high nickel content, is the micro-cracks, which will result insimultaneous reduction of thermal stability, structural stability andcycling stability of the cathode material.

In regard to the serious defect and problem that the NCM materials witha high nickel content suffer from the micro-cracks during the cyclingprocess, the widespread solutions are focused on improving both thedoping and the cladding processes of the materials. However, the twoprocesses have limited effect on the improvement of the individualmulticrystal particles, especially for the multicrystal materials with anarrow range of particle distribution. As a result, it is necessary todevelop a new type of multicrystal material and an adaptive processthereof.

The Chinese patent application CN103811744A discloses a method forpreparing a ternary cathode material of a lithium ion battery. Themethod comprises the following steps: initially preparing an aggregatematerial A from a lithium source and a precursor, preparing asingle-crystal or quasi single crystal material B from a lithium sourceand a precursor, uniformly mixing the aggregate material A and thesingle-crystal or quasi single crystal material B, sintering to form amaterial C, and cladding the powder of said material C with a coating,thereby obtaining the lithium-ion ternary cathode material. Themulticrystal and the single-crystal or quasi single crystal ternarymaterial with different granularity and shapes are mixed, and thesingle-crystal particles can be effectively arranged among the aggregateparticles, so that the graded materials are in full contact with aconductive agent and an adhesive, the space utilization rate and thecompaction density of the materials can be both improved, such that thevolume energy density of the materials is improved, the electricalproperty of the materials is fully exerted, the effect of improving heatstability of the material is produced, and the safety of the battery isenhanced. However, the process is complicated, and requires a high cost,it is not conducive to the practical production.

CN109524642A discloses a method for preparing a hybrid ternary cathodematerial. The method comprises the following steps: (1) mixing a ternarymaterial precursor A, a ternary material precursor B and a lithiumsource to obtain an initial mixture; (2) performing a first sintering onthe initial mixture at the temperature of 350-550° C., grinding thesintered material, and performing a second sintering at the temperatureof 750-1,150° C., so as to obtain the diversified hybrid ternary cathodematerial in which the secondary particle multicrystal and the singlecrystal/ quasi single crystal morphology coexist, thereby improving thecompaction density and the cycle stability of the material and reducingthe preparation costs. It is well known among those skilled in the artthat the sintering process after adding a lithium source and mixinguniformly is crucial to the materials, and the proportionality,sintering temperature and sintering time are different during theprocess of sintering the precursors having different Ni content to formthe optimal conditions, whereas the prior art uniformly sinters twoprecursors having different Ni content, it cannot balance and makecompromise such that the cathode material formed by sintering twoprecursors having different Ni content reaches the optimal performance.

CN110970602A discloses a cathode active material, wherein a low-nickelsingle crystal material and a high-nickel multicrystal material aremixed as the cathode active material; however, the finally producedmaterial has a significantly reduced capacity relative to thehigh-nickel multicrystal material, so that the advantages of thehigh-nickel material cannot be really exploited.

SUMMARY

The present disclosure aims to overcome the problems in the prior artwith respect to the decreased stability and reduced capacity of the highnickel cathode material due to an existence of micro-cracks in the highnickel cathode material, and provides a cathode material, a preparationmethod and a use thereof, a cathode electrode of lithium ion battery,and a lithium ion battery. The cathode material comprises multicrystalparticles A and single crystal particles or quasi single crystalparticles B, whereby it can significantly suppress generation ofmicro-cracks in the cathode material, and enhance the particle strengthof the cathode material, so that the cathode material has a highcompaction density and a high compressive strength, thereby ensuringthat a battery comprising the cathode material has a high volumetricenergy density and a relatively long cycle life.

In order to fulfill the above purpose, a first aspect of the presentdisclosure provides a cathode material, wherein the cathode materialcomprises multicrystal particles A and single crystal particles or quasisingle crystal particles B;

the particle diameters D₅, D₅₀ and D₉₅ of the cathode material satisfythe relationship shown in Formula I:

$\begin{matrix}{1.5 \leq \text{K95=}{\left( {\text{D}_{95}\text{-D}_{5}} \right)/{\text{D}_{50} \leq 2.5}}} & \text{­­­Formula I.}\end{matrix}$

A second aspect of the present disclosure provides a method forpreparing the aforementioned cathode material comprising the followingsteps:

-   (1) subjecting a transition metal precursor    Ni_(x1)Co_(y1)Mn_(z1)(OH)₂, lithium salt, and an optional additive    to blending and a first sintering to obtain a first sintered    material;-   (2) subjecting the first sintered material and an optional    conductive graphite and/or conductive polymer to blending and a    second sintering to obtain multicrystal particles A;-   (3) subjecting a transition metal precursor    Ni_(x2)Co_(y2)Mn_(z2)(OH) ₂, lithium salt and an optional additive    to blending and a third sintering to obtain single crystal particles    or quasi single crystal particles B;-   (4) mixing the multicrystal particles A with the single crystal    particles or quasi single crystal particles B to prepare the cathode    material;    -   wherein x1+y1+z1=1, 0.5≤x1≤1, 0≤y1≤0.5, 0≤z1≤0.5;    -   x2+y2+z2=1, 0.5≤x2≤1, 0≤y2≤0.5, 0≤z2≤0.5, -0.05≤x1-x2≤0.05.

In a third aspect, the present disclosure provides a use of theaforementioned cathode material in a lithium ion battery.

In a fourth aspect, the present disclosure provides a cathode electrodeof lithium ion battery, wherein the cathode electrode of lithium ionbattery is prepared with the aforementioned cathode material.

A fifth aspect of the present disclosure provides a lithium ion battery,wherein the lithium ion battery comprises the aforementioned cathodeelectrode of lithium ion battery.

Due to the above technical solution, the cathode material, a preparationmethod and a use thereof, a cathode electrode of lithium ion battery,and a lithium ion battery provided by the present disclosure produce thefollowing favorable effects:

(1) in the present disclosure, the cathode material comprisesmulticrystal particles A and single crystal particles or quasi singlecrystal particles B, whereby it can significantly suppress generation ofmicro-cracks in the cathode material, and enhance the particle strengthof the cathode material, in particular, the multicrystal particles A areable to suppress the generation of micro-cracks, the single crystalparticles or quasi single crystal particles are capable of effectivelylimiting the cracking of the particles A, and ultimately cause that thecathode material has a high compaction density and a high compressivestrength, thereby ensuring that a battery comprising the cathodematerial has a high volumetric energy density and a relatively longcycle life.

(2) Further, the cathode material in the present disclosure comprisesmulticrystal particles A having a relatively high grain strength, andfurthermore, the inclusion of a cladding layer in the multicrystalparticles A enables the multicrystal particles A to have a certainelasticity, thereby reducing the proportion of the cathode material thusobtained that is crushed during a process of grinding the electrode, andthe extrusion on the current collector is relatively small; on the otherhand, the high-strength cathode particles can also suppress thegeneration of micro-cracks in the material during the charging anddischarging process.

(3) Further, the present disclosure defines a solution of separatelypreparing the multicrystal particles A and the single crystal or quasisingle crystal particles B, so that the two materials obtain the optimumproperties respectively, and blending the multicrystal particles A andthe single-crystal or quasi single crystal particles B having a similarcontent with Ni, the safety and cycle stability of the cathode materialcan be remarkably improved under a premise of maintaining high chargeand discharge capacity of the multicrystal particles A having a highnickel content.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the Scanning Electron Microscopy (SEM) image of thecathode material of Example 1 of the present disclosure.

FIG. 2 illustrates the mapping diagram of the distribution of the carbon(C) element of the cathode material of Example 1 of the presentdisclosure.

FIG. 3 illustrates the fracture pressure-deformation curve of thecathode material particles of Example 1 of the present disclosure underthe micromechanical testing machine.

FIG. 4 illustrates the cycle curves of the pouch cells produced from thecathode material prepared in Example 1 and the sample in ComparativeExample 1, respectively.

FIG. 5 illustrates the cross-sectional view of a cathode electrodeprepared in Example 1 after subjecting to rolling.

DETAILED DESCRIPTION

The terminals and any value of the ranges disclosed herein are notlimited to the precise ranges or values, such ranges or values shall becomprehended as comprising the values adjacent to the ranges or values.As for numerical ranges, the endpoint values of the various ranges, theendpoint values and the individual point value of the various ranges,and the individual point values may be combined with one another toproduce one or more new numerical ranges, which should be deemed havebeen specifically disclosed herein.

A first aspect of the present disclosure provides a cathode material,wherein the cathode material comprises multicrystal particles A andsingle crystal particles or quasi single crystal particles B;

the particle diameters D₅, D₅₀ and D₉₅ of the cathode material satisfythe relationship shown in Formula I:

$\begin{matrix}{1.5 \leq \text{K95=}{\left( {\text{D}_{95}\text{-D}_{5}} \right)/{\text{D}_{50} \leq 2.5}}} & \text{­­­Formula I.}\end{matrix}$

In the present disclosure, when the cathode material comprisesmulticrystal particles A and single crystal particles or quasi singlecrystal particles B, and the particle diameters D₅, D₅₀ and D₉₅ of thecathode material satisfy the aforementioned relationship, it cansignificantly suppress generation of micro-cracks in the cathodematerial, and enhance the particle strength of the cathode material, inparticular, the multicrystal particles A are able to suppress thegeneration of micro-cracks, the single crystal particles or quasi singlecrystal particles are capable of effectively limiting the cracking ofthe particles A, and ultimately cause that the cathode material has ahigh compaction density and a high compressive strength, therebyensuring that a battery comprising the cathode material has a highvolumetric energy density and a relatively long cycle life.

In the present disclosure, the particle diameters D₅, D₅₀ and D₉₅ of thecathode material are measured by a laser particle analyzer.

According to the present disclosure, 1.5≤K95≤2.

According to the present disclosure, the multicrystal particles A have aparticle diameter D₅₀ within a range of 7-22 µm.

Further, the multicrystal particles A have a particle diameter D₅₀within a range of 11-20 µm.

According to the present disclosure, the particle diameters D₅, D₅₀ andD₉₅ of the multicrystal particles A satisfy the relationship shown inFormula II:

$\begin{matrix}{0 < \text{K}_{\text{A}}95\text{=}{\left( {\text{D}_{95}\text{-D}_{5}} \right)/{\text{D}_{50} \leq 1}}} & \text{­­­Formula II.}\end{matrix}$

In the present disclosure, when the particle diameters D₅, D₅₀ and D₉₅of the multicrystal particles A satisfy the aforementioned relationship,the cathode material particles can exhibit excellent uniformity andhomogeneity, such that the cathode material particles have acontrollable extent of shrinkage and expansion during long-term use, andthe crystal structure on the surface of the material is more stable, andcycle stability during the long-term use is desirable.

Further, 0.55<K_(A)95=(D₉₅-D5)/D₅₀≤0.95.

According to the present disclosure, the single crystal particles orquasi single crystal particles B have a particle diameter D₅₀ within arange of 0.2-7 µm.

Further, the single crystal particles or quasi single crystal particlesB have a particle diameter D₅₀ within a range of 2-5 µm.

According to the present disclosure, the particle diameters D₅, D₅₀ andD₉₅ of the single crystal particles or quasi single crystal particles Bsatisfy the relationship shown in Formula III:

$\begin{matrix}{0.2 \leq \text{K}_{\text{B}}95\text{=}{\left( {\text{D}_{95}\text{-D}_{5}} \right)/{\text{D}_{50} \leq 3}}} & \text{­­­Formula III.}\end{matrix}$

Further, 1.5≤K_(B)95=(D₉₅-D₅)/D₅₀≤2.5.

According to the present disclosure, the cathode material has acomposition represented by Formula (1):

-   in the Formula (1), 0≤a≤0.3, 0<x≤1, 0≤y≤1, 0≤z≤1, 0≤k≤0.1, 0≤w≤0.1,    M is at least one selected from the group consisting of B, Na, K,    Mg, Al, Ca, Ti, Fe, Zn, Sr, Y, Zr, Nb, Mo, Sn, Ba, Ta and W;-   N is at least one selected from the group consisting of B, Mg, Al,    Ti, V, Sr, Y, Zr, Nb, Mo and W;-   J is at least one selected from the group consisting of F, Cl and P.

According to the present disclosure, the surface of the multicrystalparticles A is coated with a cladding layer P.

In the present disclosure, the surface of the multicrystal particles Ais coated with a cladding layer P, enabling the multicrystal particles Ato have a certain elasticity, thereby reducing the proportion of thecathode material that is crushed during a process of grinding theelectrode decreasing the extrusion on the current collector, andsuppressing the generation of micro-cracks on the cathode materialduring the charging and discharging process.

According to the present disclosure, a mass ratio of the multicrystalparticles A to the cladding layer P is 1:0-0.05, based on the totalweight of the multicrystal particles A.

Further, a mass ratio of the multicrystal particles A to the claddinglayer P is 1:0.001-0.02, based on the total weight of the multicrystalparticles A.

According to the present disclosure, the cladding layer P is provided byconductive graphite and/or conductive polymer.

Based on the present disclosure, the conductive polymer is at least oneselected from the group consisting of polyaniline, polypyrrole,polythiophene, polyacetylene, poly(para-phenylene sulfide),poly(3,4-ethylenedioxythiophene) and polyphenylacetylene.

In the present disclosure, the multicrystal particles A have acomposition represented by Formula (2):

-   in the Formula (2), 0≤a1≤0.3, 0<x1≤1, 0≤y1≤1, 0≤z1≤1, 0≤k1≤0.1,    0≤w1≤0.1, and M′ is at least one selected from the group consisting    of B, Na, K, Mg, Al, Ca, Ti, Fe, Zn, Sr, Y, Zr, Nb, Mo, Sn, Ba, Ta    and W;-   N′ is at least one selected from the group consisting of B, Mg, Al,    Ti, V, Sr, Y, Zr, Nb, Mo and W;-   J′ is at least one selected from the group consisting of F, Cl and    P.

In the present disclosure, the single crystal particles or quasi singlecrystal particles B have a composition represented by Formula (3):

In formula (3), 0≤a2≤0.3, 0<x2≤1, 0≤y2≤1, 0≤z2≤1, 0≤k2≤0.1, 0≤w1≤0.1, M″is at least one selected from the group consisting of B, Na, K, Mg, Al,Ca, Ti, Fe, Zn, Sr, Y, Zr, Nb, Mo, Sn, Ba, Ta and W;

-   N″ is at least one selected from the group consisting of B, Mg, Al,    Ti, V, Sr, Y, Zr, Nb, Mo and W;-   J″ is at least one selected from the group consisting of F, Cl and    P.

According to the present disclosure, a mass ratio of the multicrystalparticles A to the single crystal particles or quasi single crystalparticles B in the cathode material is 0.01-9:1.

Further, a mass ratio of the multicrystal particles A to the singlecrystal particles or quasi single crystal particles B is 0.25-4:1.

According to the present disclosure, an individual particle strength ofthe multicrystal particles A in a test of the micro-mechanical testingmachine is greater than or equal to 50 MPa; a deformation quantity ofthe multicrystal particles A prior to fracture is within a rangeD₅₀x(5-25%) of the multicrystal particles A.

In the present disclosure, under a pressure condition, the multicrystalparticles A initially undergo a minute deformation and eventually breakdown completely along with an increased pressure. As shown in FIG. 4 ,the deformation quantity of the particles initially exhibits a tendencyof slow change under a circumstance of small pressure, the variation atthe moment represents the strength of said multicrystal particles A, thegreater is the strength, the longer is the slowly increased displacementdiameter. As the pressure increases, the particle cracks and itsdeformation quantity increases rapidly and shows a linear change, thisstage has a strong relationship with the internal crystal structure ofthe initial multicrystal particles A. That is, the slower is thedisplacement diameter of the multicrystal particles under the pressurecondition prior to the linear change, the larger is the deformationquantity before the cracking, indicating the higher is the strength ofthe particles.

In the present disclosure, an individual particle strength of themulticrystal particles A in a test of the micro-mechanical testingmachine is within a range of 50-200 MPa; a deformation quantity of themulticrystal particles A prior to fracture is within a rangeD₅₀×(10-25%) of the multicrystal particles A.

According to the present disclosure, the cathode material has a powdercompaction density greater than or equal to 3.5 g/cm³ under a pressurecondition of20 kN.

Further, the cathode material has a powder compaction density within arange of 3.5-4.5 g/cm³ under a pressure condition of 20 kN.

According to the present disclosure, a specific surface area of thecathode material is denoted as A1, the specific surface area of thecathode material after a pressure fracturing of 4.5 T is denoted as A2;

wherein (A2-A1)/A1×100%≤40%.

Further, (A2-A1)/A1×100% is within a range of 5-30%.

In a second aspect, the present disclosure provides a method forpreparing the aforementioned cathode material comprising the followingsteps:

-   (1) subjecting a transition metal precursor    Ni_(x1)Co_(y1)Mn_(z1)(OH)₂, lithium salt, and an optional additive    to blending and a first sintering to obtain a first sintered    material;-   (2) subjecting the first sintered material and an optional    conductive graphite and/or conductive polymer to blending and a    second sintering to obtain multicrystal particles A;-   (3) subjecting a transition metal precursor    Ni_(x2)Co_(y2)Mn_(z2)(OH)₂, lithium salt and an optional additive to    blending and a third sintering to obtain single crystal particles or    quasi single crystal particles B;-   (4) mixing the multicrystal particles A with the single crystal    particles or quasi single crystal particles B to prepare the cathode    material;    -   wherein x1+y1+z1=1, 0.5≤x1≤1, 0≤y1≤0.5, 0≤z1≤0.5;    -   x2+y2+z2=1, 0.5≤x2≤1, 0≤y2≤0.5, 0≤z2≤0.5, -0.05≤x1-x2≤0.05.

In the present disclosure, separately preparing the multicrystalparticles A and the single crystal particles or quasi single crystalparticles B, so that the two materials obtain the optimum propertiesrespectively, and blending the multicrystal particles A and thesingle-crystal or quasi single crystal particles B, the safety and cyclestability of the cathode material can be remarkably improved under apremise of maintaining high charge and discharge capacity of themulticrystal particles A having a high nickel content.

According to the present disclosure, the additive is at least oneselected from the group consisting of lithium compounds, boroncompounds, tungsten compounds, neodymium compounds, aluminum compounds,zirconium compounds, magnesium compounds and chlorides.

In the present disclosure, the lithium compound is at least one selectedfrom the group consisting of Li₂O, LiOH, Li₂CO₃, LiCl, LiF, Li₃PO₄ andLiBO₂.

The boron compound is at least one selected from the group consisting ofB₂O₃, H₃BO₃, Na₂B₄O₇ and Li₂B₄O₇.

The tungsten compound is at least one selected from the group consistingof WO₂, WO₃, Na₂WO₄, Li₂W₂O₂ and Li₂WO₄.

The neodymium compound is at least one selected from the groupconsisting of Nb₂O₅, NbO₂, Nb₂O₃ and NbCls.

The aluminum compound is at least one selected from the group consistingof Al₂O₃, Al(OH)₃ and AlOOH.

The zirconium compound is at least one selected from the groupconsisting of ZrO₂, Zr(OH)₄ and ZrSiO₄.

The magnesium compound is at least one selected from the groupconsisting of MgO, MgCl₂ and Mg(OH)₂.

The chloride is at least one selected from the group consisting of NaCl,KCl and BaCl₂.

According to the present disclosure, the molar ratio of the transitionmetal precursor Ni_(x1)Co_(y1)Mn_(z1)(OH)₂, the lithium salt and theadditive in step (1) is 1:0.99-1.1:0-1.

According to the present disclosure, the first sintering conditionscomprise a sintering temperature of 650-850° C. and a sintering time of15-30 h.

Further, the first sintering conditions comprise a sintering temperatureof 680-800° C. and a sintering time of 16-25 h.

According to the present disclosure, the first sintering comprises atemperature rise stage and a constant temperature stage; wherein a ratioof the temperature rise time tr of the temperature rise stage to theconstant temperature time tc of the constant temperature stage in step(1) satisfies:

$\begin{matrix}{0.5 \leq {\text{t}_{\text{r}}/{\text{t}_{\text{c}} \leq \text{2}\text{.5}}}} & \text{­­­(4)}\end{matrix}$

In the present disclosure, when the ratio of the temperature rise timeto the constant temperature time of the sintering process falls into theabove range, the reaction process of the material during the synthesisprocess can be effectively controlled, so that the surface of theprimary particles is more uniform and smooth, and the secondaryparticles are denser. The residual alkali on the surface is alsoeffectively controlled, and the strength of said particles issignificantly enhanced. Therefore, the cracking degree of the materialis effectively reduced and the cycle stability and safety of thematerial are improved during the long-term use.

Further, 0.6≤t_(r)/t_(c)≤2.

According to the present disclosure, a mass ratio of the first sinteredmaterial to the conductive graphite and/or the conductive polymer is1:0-0.05.

Further, the mass ratio of the first sintered material to the conductivegraphite and/or the conductive polymer is 1:0.001-0.02.

In a specific embodiment of the present disclosure, the first sinteredmaterial, the conductive graphite and the conductive polymer aresubjected to blending and a second sintering to obtain multicrystalparticles A.

In particular, the mass ratio of the first sintered material, theconductive graphite and the conductive polymer is 1: 0.001-0.01:0.001-0.01, preferably 1: 0.002-0.008: 0.002-0.008.

According to the present disclosure, the second sintering conditionscomprise a sintering temperature of 100-500° C. and a sintering time of4-12 h.

Further, the second sintering conditions comprise a sinteringtemperature of 200-400° C. and a sintering time of 6-10 h.

According to the present disclosure, a molar ratio of the transitionmetal precursor Ni_(x2)Co_(y2)Mn_(z2)(OH)₂, the lithium salt and theadditive in step (3) is 1: 0.99-1.1: 0-1.

According to the present disclosure, the third sintering conditionscomprise a sintering temperature of 800-1,200° C. and a sintering timeof 15-30 h.

Further, the third sintering conditions comprise a sintering temperatureof 850-1,000° C. and a sintering time of 15-25 h.

According to the present disclosure, a mass ratio of the multicrystalparticles A to the single crystal particles or quasi single crystalparticles B is 0.01-9:1, preferably 0.25-4:1.

A third aspect of the present disclosure provides a use of theaforementioned cathode material in a lithium ion battery.

A fourth aspect of the present disclosure provides a cathode electrodeof lithium ion battery, wherein the cathode electrode of lithium ionbattery is prepared with the aforementioned cathode material.

In the present disclosure, the cathode electrode of lithium ion batterycan be prepared according to the conventional method in the art, inparticular, the cathode electrode of lithium ion battery may be preparedby dispersing the cathode material, a conductive agent and a binder inan organic solvent (e.g., NMP) according to a mass ratio of90-98:0-8:0.5-8, stirring uniformly and performing a slurryhomogenization treatment, then coating the produced slurry on analuminum foil, drying, cutting and rolling the foil.

In the present disclosure, when the compaction density of the cathodeelectrode of lithium ion battery is within a range of 3.4-3.6 g/cm³, thedeformation quantity of the aluminum foil caused by an extrusion of thecathode particles against the aluminum foil is less than 30%.

In the present disclosure, the deformation quantity of the aluminum foilis measured with a straight scale.

A fifth aspect of the present disclosure provides a lithium ion battery,wherein the lithium ion battery comprises the aforementioned cathodeelectrode of lithium ion battery.

In the present disclosure, a lithium-ion battery may be prepared with aconventional method in the art. Specifically, a lithium-ion battery ismanufactured by subjecting a cathode electrode of lithium ion battery,an anode electrode and separators to winding, encapsulating into ahousing, injecting with an electrolyte and sealing.

The present disclosure will be described in detail with reference toexamples. In the following example,

-   the particle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles    A, single crystal particles or quasi single crystal particles B, and    the cathode material were measured by using the following method:-   the test was carried out by using a laser particle analyzer with a    model Mastersizer2000. The “sample test time” and “background test    time” for the test number items in the “Measure” in the software    were modified into 6 s; the cycle number of the cycle item was    measured for 3 times, the delay time was set at 5 s, an average    result record from the measurement was created by clicking. Next,    the “start” button was clicked to automatically operate the    measurement background; after the automatic measurement was    completed, 40 mL of sodium pyrophosphate was initially added, a    small amount of sample was subsequently added with a drug spoon    until the shading degree reached ½ of the 10-20% visual area, the    “start” button was clicked, the three measurement results and an    average thereof were finally recorded.

The compaction density of a cathode electrode was measured by using thefollowing method:

The test was performed using a MCP-PD51 powder resistance meter. A cleanand dry aluminum foil was taken, 4 g of the sample to be measured wasweighted, and added into the mounted mold, it was required that thematerial did not stain on inner wall of the mold, the mold was gentlyshook left and right to flatten the material contained therein, thesample quality and batch number of the sample were input the testingsoftware. The material was subjected to a pressurization test, and thepressurization time was controlled to be about 15-20 min, thepressurization process was stopped when the pressure reached 20 KN, thepressure was stabilized for 30 s, the pressure was restored to 20 KN ifthe pressure dropped. The testing of sample was then started, and thethickness was recorded after the resistance test was completed, thethickness was finally calculated to obtain the compaction density.

The specific surface area of the cathode material was measured accordingto the following method:

-   the test was performed using a MCP-PD51 powder resistance meter. A    clean and dry aluminum foil was taken, 5 g of the sample to be    measured was weighted, and added into the mounted mold, it was    required that the material did not stain on inner wall of the mold,    the mold was gently shook left and right to flatten the material    contained therein, the sample quality and batch number of the sample    were input the testing software. The mold was mounted on a lifter    and subjected to testing by applying the pressures of 0 T (ton)    (Ref), 1.5 T, 2.5 T, 3.5 T and 4.5 T, respectively. The    pressurization time was controlled to be about 15-20 min, the    pressurization process was stopped when the pressure reached a    target value, the pressure was stabilized for 30 s, the fractured    particles were taken out for subjecting to the specific surface area    test;-   the specific surface area test was carried out using a Tri-star 3020    specific surface area tester, wherein 3 g of sample was weighted,    the sample tube was mounted on a vacuum joint at the degassing    station port. The heating temperature was set at 300° C., the    degassing time was 120 min, and after completion of the degassing    process, the sample tube was cooled down. The mass of an empty    sample tube and the total mass of degassed samples and the sample    tube were input the software interface of the tester, the data of    specific surface area (BET method) output after calculation of the    software was recorded, so as to accomplish the specific surface area    testing of the cathode material sample;-   the particle strength of the cathode material was measured by    adopting the following method:    -   the measurement was performed using a MCT-210 miniature        compression testing machine. The MCT-210 testing software was        first opened, the sample platform was clamped at a middle        position of the tabletting, there was not sliding, and ensured        that a height of the sample platform was at least 3 cm below the        objective lens; the LED light switch was turned on in the main        machine, and the hand wheel in the bottom right position in the        main machine was shaken to adjust the height of the sample        platform till the image of the specimen pellet in the display        window of a CCD image was legible, the “start testing” button        was clicked to measure the particle diameter, the image of        particles before compression was saved; the hand wheel was        rotated so as to move the particle apex to the lens focus, the        sample platform was pushed to the right to underneath a platen,        the compression test was started; after completion of the        compression, the sample platform was pushed to the left to        underneath the objective lens, the hand wheel was rotated till        the image obtained after compression was legible, the images        were saved.

The surface morphology of the cathode material and the surface elementdistribution of the cathode material were measured by using a ScanningElectron Microscope (SEM);

the electrochemical performance and safety properties of the lithium-ionbattery were measured and tested according to the National StandardGB/T18287-2000 of lithium-ion battery of China.

Example 1

-   (1) Preparation of multicrystal particles A: the following compounds    were calculated in terms of the molar ratio, wherein the molar ratio    of transition metal hydroxide precursor    Ni_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH: LiF: ZrO₂ was 1: 1.03: 0.01:    0.005, the compounds were blended uniformly and then subjected to    sintering at 780° C. for 24 h to obtain a first sintered material;    wherein the temperature rise time was 12 h, and the constant    temperature time was 12 h;-   (2) the first sintered material, artificial graphite and conductive    polyaniline were blended according to a mass ratio of 1: 0.005:    0.005, the compounds were blended by using a high-speed mixer, and    then subjected to sintering at 350° C. for 10 h, to finally    obtaining the multicrystal particles A coated with a cladding layer    P on the surface thereof, the multicrystal particles A had a    composition    (Li_(1.03)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.01))0.01P.    The particle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles    A were 8.5 µm, 12.6 µm and 18.4 µm, respectively, and K_(A)95 was    0.78; an average particle strength was 98 MPa by testing with a    micro-mechanical testing machine, a deformation quantity of the    multicrystal particles A prior to fracture was 2.5 µm, which    accounted for 19.8% of D₅₀ of the particles prior to fracture.

(3) Preparation of single crystal particles or quasi single crystalparticles B: the following compounds were calculated in terms of molarratio, wherein the molar ratio of a transition metal hydroxide precursorNi_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH: ZrO₂ was 1: 1.01: 0.005, thecompounds were blended uniformly and then subjected to sintering at 870°C. for 24 h to obtain the single crystal particles or quasi singlecrystal particles B having a composition ofLi_(1.01)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂, wherein the particlediameters D₅, D₅₀ and D₉₅ of the single crystal particles or quasisingle crystal particles B were 2.6 µm, 5.6 µm and 11.3 µm,respectively, and the K_(B)95 was 1.55.

(4) Preparation of cathode material: the multicrystal particles A andthe single crystal particles or quasi single crystal particles B wereblended according to a mass ratio of 70:30, the compounds were blendedby using a high-speed mixer to obtain a cathode material, thecomposition of said cathode material was(Li_(1.024)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.007))0.007P.The particle diameters D₅, D₅₀ and D₉₅ of the cathode material were 2.3µm, 10.7 µm and 20.5 µm, respectively, and K95 was 1.70.

Upon testing, the cathode material had a powder compaction densityreached 3.65 g/cm³ under a pressure condition of 20 kN, the specificsurface area A1 of the cathode material was 0.56 m²/g; the specificsurface area A2 of the cathode material was 0.68 m²/g after compressionwith a pressure of 4.5 T, (A2-A1)/A1×100% was 21%.

The SEM image and the mapping diagram of the distribution of the carbonelements of the cathode material of Example 1 were shown in FIG. 1 andFIG. 2 , respectively. As illustrated from FIG. 1 , the cathode materialwas composed of the multicrystal particles and the single crystalparticles or quasi single crystal particles, wherein a layer of claddingsubstance was uniformly dispersed on the surface of large particles.Further, FIG. 2 illustrated the mapping diagram of the distribution ofcarbon elements of FIG. 1 , which can confirm that an elastic claddinglayer was uniformly dispersed on the surface of large particles.

FIG. 3 illustrated a fracture pressure-deformation curve of theindividual grain of multicrystal particles A of Example 1 in the testingperformed by the micro-mechanical testing machine; as shown in FIG. 3 ,the displacement diameter of particles was increased slowly along withthe increasing pressure, and the displacement diameter increased sharplydue to the continuous enlargement of the pressure, the particles werefinally fractured.

Example 2

-   (1) Preparation of multicrystal particles A: the following compounds    were calculated in terms of the molar ratio, wherein the molar ratio    of transition metal hydroxide precursor    Ni_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH: ZrO₂ was 1: 1.04: 0.005, the    compounds were blended uniformly and then subjected to sintering at    700° C. for 15 h to obtain a first sintered material; wherein the    temperature rise time was 7 h, and the constant temperature time    was8 h;-   (2) the first sintered material, artificial graphite and conductive    polyaniline were blended according to a mass ratio of 1: 0.005:    0.005, the compounds were blended by using a high-speed mixer, and    then subjected to sintering at 350° C. for 10 h, to finally    obtaining the multicrystal particles A coated with a cladding layer    P on the surface thereof, the multicrystal particles A had a    composition    (Li_(1.04)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂)0.01P. The    particle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles A    were 11.4 µm, 16.7 µm and 24.5 µm, respectively, and K_(A)95 was    0.78; an average particle strength was 95 MPa by testing with a    micro-mechanical testing machine, a deformation quantity of the    multicrystal particles A prior to fracture was 3.2 µm, which    accounted for 19.2% of D₅₀ of the particles prior to fracture.

(3) Preparation of single crystal particles or quasi single crystalparticles B: the following compounds were calculated in terms of molarratio, wherein the molar ratio of a transition metal hydroxide precursorNi_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH was 1: 1.02, the compounds wereblended uniformly and then subjected to sintering at 870° C. for 24 h toobtain the single crystal particles or quasi single crystal particles Bhaving a composition of Li_(1.02)(Ni_(0.83)Co_(0.06)Mn_(0.11))O₂,wherein the particle diameters D₅, D₅₀ and D₉₅ of the single crystalparticles or quasi single crystal particles B were 1.8 µm, 3.7 µm and7.3 µm, respectively, and the K_(B)95 was 1.48.

(4) Preparation of cathode material: the multicrystal particles A andthe single crystal particles or quasi single crystal particles B wereblended according to a mass ratio of 70:30, the compounds were blendedby using a high-speed mixer to obtain a cathode material, thecomposition of said cathode material was(Li_(1.034)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.0035))O₂)0.007P. Theparticle diameters D₅, D₅₀ and D₉₅ of the cathode material were 2.0 µm,13.2 µm and 26.6 µm, respectively, and K95 was 1.86.

Upon testing, the cathode material had a powder compaction densityreached 3.60 g/cm³ under a pressure condition of 20 kN, the specificsurface area A1 of the cathode material was 0.61 m²/g; the specificsurface area A2 of the cathode material was 0.74 m²/g after compressionwith a pressure of 4.5 T, (A2-A1)/A1×100% was 21%.

Example 3

-   (1) Preparation of multicrystal particles A: the following compounds    were calculated in terms of the molar ratio, wherein the molar ratio    of transition metal hydroxide precursor    Ni_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH: LiF: ZrO₂ was 1: 1.03: 0.01:    0.005, the compounds were blended uniformly and then subjected to    sintering at 780° C. for 24 h to obtain a first sintered material;    wherein the temperature rise time was 12 h, and the constant    temperature time was 12 h;-   (2) the first sintered material and the artificial graphite were    blended according to a mass ratio of 1: 0.01, the compounds were    blended by using a high-speed mixer, and then subjected to sintering    at 350° C. for 10 h, to finally obtaining the multicrystal particles    A coated with a cladding layer P on the surface thereof, the    multicrystal particles A had a composition    (Li_(1.03)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.01))0.01P.    The particle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles    A were 8.4 µm, 12.5 µm and 18.3 µm, respectively, and K_(A)95 was    0.79; an average particle strength was 89 MPa by testing with a    micro-mechanical testing machine, a deformation quantity of the    multicrystal particles A prior to fracture was 2.7 µm, which    accounted for 21.6% of D₅₀ of the particles prior to fracture.

(3) Preparation of single crystal particles or quasi single crystalparticles B was performed according to step (3) of Example 1.

(4) Preparation of cathode material: the multicrystal particles A andthe single crystal particles or quasi single crystal particles B wereblended according to a mass ratio of 70:30, the compounds were blendedby using a high-speed mixer to obtain a cathode material, thecomposition of said cathode material was(Li_(1.024)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.007))0.007P.The particle diameters D₅, D₅₀ and D₉₅ of the cathode material were 2.3µm, 10.7 µm and 20.4 µm, respectively, and K95 was 1.69.

Upon testing, the cathode material had a powder compaction densityreached 3.63 g/cm³ under a pressure condition of 20 kN, the specificsurface area A1 of the cathode material was 0.58 m²/g; the specificsurface area A2 of the cathode material was 0.71 m²/g after compressionwith a pressure of 4.5 T, (A2-A₁)/A₁×100% was 22%.

Example 4

-   (1) Preparation of multicrystal particles A: the following compounds    were calculated in terms of the molar ratio, wherein the molar ratio    of transition metal hydroxide precursor    Ni_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH: LiF: ZrO₂ was 1: 1.03: 0.01:    0.005, the compounds were blended uniformly and then subjected to    sintering at 780° C. for 24 h to obtain a first sintered material;    wherein the temperature rise time was 18 h, and the constant    temperature time was 9 h;-   (2) the step (2) of Example 4 was identical with step (2) of Example    1, to obtain the multicrystal particles A having a composition    (Li_(1.03)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.01))0.01P.    The particle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles    A were 6.2 µm, 11.9 µm and 17.3 µm, respectively, and K_(A)95 was    0.93; an average particle strength was 102 MPa by testing with a    micro-mechanical testing machine, a deformation quantity of the    multicrystal particles A prior to fracture was 2 µm, which accounted    for 16.8% of D₅₀ of the particles prior to fracture.

(3) The step (3) of Example 4 was identical with step (3) of Example 1.

(4) Preparation of cathode material: the multicrystal particles A andthe single crystal particles or quasi single crystal particles B wereblended according to a mass ratio of 80:20, the compounds were blendedby using a high-speed mixer to obtain a cathode material, thecomposition of said cathode material was(Li_(1.026)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.008))0.008P.The particle diameters D₅, D₅₀ and D₉₅ of the cathode material were 2.6µm, 11.4 µm and 21.2 µm, respectively, and K95 was 1.63.

Upon testing, the cathode material had a powder compaction densityreached 3.70 g/cm³ under a pressure condition of 20 kN, the specificsurface area A1 of the cathode material was 0.50 m²/g; the specificsurface area A2 of the cathode material was 0.58 m²/g after compressionwith a pressure of 4.5 T, (A2-A1)/A1×100% was 16%.

Example 5

The cathode material was prepared according to the method of Example 1,except that step (2) was not carried out, the first sintered materialobtained from step (1) was multicrystal particles A having a compositionof Li_(1.03)(Ni_(0.83)Co_(0.060)Mn_(0.11)Zr_(0.005))O₂F_(0.01). Theparticle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles A were9.0 µm, 13.1 µm and 19 µm, respectively, and K_(A)95 was 0.76; anaverage particle strength was 82 MPa by testing with a micro-mechanicaltesting machine, a deformation quantity of the multicrystal particles Aprior to fracture was 1.8 µm, which accounted for 13.7% of D₅₀ of theparticles prior to fracture.

Steps (3) and (4) of Example 4 were carried out according to steps (3)and (4) of Example 1. The cathode material having a composition of(Li_(1.024)(Ni_(0.83)Co_(0.06)Mn_(0.11)Zr_(0.005))O₂F_(0.007))0.007P wasfinally prepared. The particle diameters D₅, D₅₀ and D₉₅ of the cathodematerial were 2.5 µm, 10.9 µm and 20.5 µm, respectively, and K95 was1.65.

Upon testing, the cathode material had a powder compaction densityreached 3.55 g/cm³ under a pressure condition of 20 kN, the specificsurface area A1 of the cathode material was 0.54 m²/g; the specificsurface area A2 of the cathode material was 0.71 m²/g after compressionwith a pressure of 4.5 T, (A2-A1)/A1×100% was 30%.

Comparative Example 1

A cathode material was prepared according to the method of Example 1,except that steps (3) and (4) were not carried out. The multicrystalparticles A were used as the cathode material. The particle diametersD₅, D₅₀ and D₉₅ of the multicrystal particles A were 8.5 µm, 12.6 µm and18.4 µm, respectively, and K_(A)95 was 0.78; an average particlestrength was 98 MPa by testing with a micro-mechanical testing machine,a deformation quantity of the multicrystal particles A prior to fracturewas 2.5 µm, which accounted for 19.8% of D₅₀ of the particles prior tofracture.

Upon testing, the cathode material had a powder compaction density of3.2 g/cm³ under a pressure condition of 20 kN;

The specific surface area A1 of the cathode material was 0.42 m²/g; thespecific surface area A2 of the cathode material was 0.68 m²/g aftercompression with a pressure of 4.5 T, (A2-A1)/A1×100% was 62%.

Comparative Example 2

-   (1) Preparation of multicrystal particles A: the following compounds    were calculated in terms of the molar ratio, wherein the molar ratio    of transition metal hydroxide precursor    Ni_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH was 1: 1.09, the compounds    were blended uniformly and then subjected to sintering at 600° C.    for 10 h to obtain a first sintered material; wherein the    temperature rise time was 6 h, and the constant temperature time was    4 h;-   (2) the first sintered material, artificial graphite and conductive    polyaniline were blended according to a mass ratio of 1: 0.05: 0.05,    the compounds were blended by using a high-speed mixer, and then    subjected to sintering at 200° C. for 6 h, to finally obtaining the    multicrystal particles A coated with a cladding layer P on the    surface thereof, the multicrystal particles A had a composition    (Li_(1.09)(Ni_(0.83)Co_(0.06)Mn_(0.11)O₂)0.1P. The particle    diameters D₅, D₅₀ and D₉₅ of the multicrystal particles A were 4.5    µm, 10.5 µm and 21.5 µm, respectively, and K_(A)95 was 1.6; an    average particle strength was 100 MPa by testing with a    micro-mechanical testing machine, a deformation quantity of the    multicrystal particles A prior to fracture was 1.9 µm, which    accounted for 18.1% of D₅₀ of the particles prior to fracture.

(3) Preparation of single crystal particles or quasi single crystalparticles B: the following compounds were calculated in terms of molarratio, wherein the molar ratio of a transition metal hydroxide precursorNi_(0.83)Co_(0.06)Mn_(0.11)(OH)₂: LiOH: ZrO₂ was 1: 1.02: 0.01, thecompounds were blended uniformly and then subjected to sintering at1,000° C. for24 h to obtain the single crystal particles or quasi singlecrystal particles B having a composition ofLi_(1.02)(Ni_(0.83)Co_(0.83)Mn_(0.11)Zr_(0.01))O₂, wherein the particlediameters D₅, D₅₀ and D₉₅ of the single crystal particles or quasisingle crystal particles B were 1.8 µm, 4.3 µm and 11.5 µm,respectively, and the K_(B)95 was 2.25.

(4) The blending method in Comparative Example 2 was identical with thatin Example 1, the compounds were blended by using a high-speed mixer toobtain a cathode material. The particle diameters D₅, D₅₀ and D₉₅ of thecathode material were 1.6 µm, 9 µm and 24.5 µm, respectively, and K95was 2.54.

Upon testing, the cathode material had a powder compaction densityreached 3.46 g/cm³ under a pressure condition of 20 kN, the specificsurface area A1 of the cathode material was 0.33 m²/g; the specificsurface area A2 of the cathode material was 0.45 m²/g after compressionwith a pressure of 4.5 T, (A2-A1)/A1×100% was 36%.

TABLE 1 Performance parameters of the cathode material Particles AParticle s B Cathode material KA95 Particle strength /MPa Deformationquantity/% K_(B)95 K95 Compaction density /g/cm³ Specific surface areaA1/m²/g Specific surface area A2/m²/g (A2-A1)/A1×10 0% Example 1 0.78 9819.8 1.55 1.7 3.65 0.56 0.68 21 Example 2 0.78 95 19.2 1.48 1.86 3.60.61 0.74 21 Example 3 0.79 89 21.6 1.48 1.69 3.63 0.58 0.71 22 Example4 0.93 102 16.8 1.48 1.63 3.70 0.50 0.58 16 Example 5 0.76 82 13.7 1.551.65 3.55 0.54 0.71 30 Comparative Example 1 0.78 98 19.8 / 0.78 3.200.42 0.68 62 Comparative Example 2 1.6 78 18.1 2.25 2.54 3.46 0.33 0.4536

As shown in Table 1, firstly, both the compaction density and the BETincrease after fracturing under a pressure condition of 4.5 T of thecathode material after blending the multicrystal particles A with theparticles B are significantly enhanced and improved. Secondly, theelastic cladding layer on the surface of the multicrystal particles Acan effectively enhance strength of the individual particles andalleviate the cracking extent of particles during the long cyclicprocess; the K95 of the cathode material prepared in the ComparativeExamples does not fall into the protection scope of the presentdisclosure. The particles are more dispersed with weaker strength, whichis adverse to long-term cycle use.

Test Examples (1) Cathode Electrode of Lithium Ion Battery

The cathode materials prepared in the Examples and Comparative Exampleswere blended with carbon black and polyvinylidene fluoride (PVDF)according to a weight ratio of 95:2.5:2.5, the mixture was coated onaluminum foils, and subjected to drying, cutting and rolling to preparethe cathode electrode of lithium ion battery.

(2) Pouch Cell

The artificial graphite was used as the anode, the polyethylene (PE) wasused as the separators, and the cathode electrode of lithium ion batterywas used as the cathode electrode; specifically, the anode was the anodeelectrode obtained by coating the copper foil with the artificialgraphite, and subjected to drying, cutting and rolling; the PEseparators were added between the cathode electrode and the anodeelectrode, and subjected to winding, encapsulating into a housing,injecting with an electrolyte and sealing, and processed into thewinding-type pouch cell, the properties of the pouch cell were shown inTable 2.

The SEM of a cross-sectional view of a cathode electrode prepared withthe cathode electrode of Example 1 after subjecting to rolling was shownin FIG. 5 , which illustrated the presence of single crystal particlesor quasi single crystal particles B, indicating that the cathodematerial of Example 1 was capable of reducing extrusion on the currentcollector.

FIG. 4 illustrated the cycle curves of the pouch cells comprising thecathode using the cathode electrode produced from the cathode materialprepared in Example 1 and Comparative Example 1, respectively. As shownin FIG. 4 , the cycle stability of the pouch cells comprising thecathode electrodes produced from the cathode materials of Example 1 wassignificantly improved compared to the Comparative Example 1.

TABLE 2 Cathode electrode Pouch cell Compaction density /g/cm³ Dischargecapacity /mAh/g charge-discharge cycle life for 1,000 times /% Gasproduction rate stored at 60° C. for 30 days /% Example 1 3.55 205 925.5 Example 2 3.56 206 89 7.2 Example 3 3.55 204 91 6.5 Example 4 3.58203 93 4.6 Example 5 3.45 206 87 10 Comparative Example 1 3.15 204 84 30Comparative Example 2 3.35 203 86 12

As shown by Table 2, the compaction density of cathode electrodeprepared with the cathode material of the present disclosure issignificantly improved, and it effectively suppresses generation of themicro-crack in the material during the charge and discharge process, thecycle life and the aerogenesis performance are also remarkably enhanced.Secondly, the elastic cladding layer on a surface of the multicrystalparticles A also effectively buffers the extrusion of particles on thecurrent collector under a premise without substantially affecting thecapacity, the cycle life is enhanced.

The above content describes in detail the preferred embodiments of thepresent disclosure, but the present disclosure is not limited thereto. Avariety of simple modifications can be made in regard to the technicalsolutions of the present disclosure within the scope of the technicalconcept of the present disclosure, including a combination of individualtechnical features in any other suitable manner, such simplemodifications and combinations thereof shall also be regarded as thecontent disclosed by the present disclosure, each of them falls into theprotection scope of the present disclosure.

1. A cathode material comprising multicrystal particles A and singlecrystal particles or quasi single crystal particles B; the particlediameters D₅, D₅₀ and D₉₅ of the cathode material satisfy therelationship shown in Formula I: $\begin{matrix}{1.5 \leq \text{K95} = {\left( {\text{D}_{95}\text{-D}_{5}} \right)/\text{D}_{50}} \leq 2.5} & \text{­­­Formula I.}\end{matrix}$
 2. The cathode material of claim 1, wherein 1.5≤K95≤2. 3.The cathode material of claim 1, wherein the multicrystal particles Ahave a particle diameter D₅₀ within a range of 7-22 µm; and/or, theparticle diameters D₅, D₅₀ and D₉₅ of the multicrystal particles Asatisfy the relationship shown in Formula II: $\begin{matrix}{0 < \text{K}_{\text{A}}95 = {\left( {\text{D}_{95}\text{-D}_{5}} \right)/\text{D}_{50}} \leq 1} & \text{­­­Formula II;}\end{matrix}$ and/or, the single crystal particles or quasi singlecrystal particles B have a particle diameter D₅₀ within a range of 0.2-7µm; and/or, the particle diameters D₅, D₅₀ and D₉₅ of the single crystalparticles or quasi single crystal particles B satisfy the relationshipshown in Formula III: $\begin{matrix}{0.2 < \text{K}_{\text{B}}95 = {\left( {\text{D}_{95}\text{-D}_{5}} \right)/\text{D}_{50}} \leq 3} & \text{­­­Formula III.}\end{matrix}$
 4. The cathode material of claim 1, wherein the cathodematerial has a composition represented by Formula (1): $\begin{matrix}\left\lbrack {\text{Li}_{1\text{+a}}\left( {\text{Ni}_{\text{x}}\text{Co}_{\text{y}}\text{Mn}_{\text{z}}\text{M}_{\text{1-x-y-z}}} \right)\text{N}_{\text{k}}\text{O}_{2\text{-w}}\text{J}_{\text{w}}} \right\rbrack & \text{­­­(1)}\end{matrix}$ in the Formula (1), 0≤a≤0.3, 0<x≤1, 0≤y≤1, 0≤z≤1, 0≤k≤0.1,0≤w≤0.1, M is at least one selected from the group consisting of B, Na,K, Mg, Al, Ca, Ti, Fe, Zn, Sr, Y, Zr, Nb, Mo, Sn, Ba, Ta and W; N is atleast one selected from the group consisting of B, Mg, Al, Ti, V, Sr, Y,Zr, Nb, Mo and W; J is at least one selected from the group consistingof F, Cl and P.
 5. The cathode material of claim 1, wherein the surfaceof the multicrystal particles A is coated with a cladding layer P;and/or, a mass ratio of the multicrystal particles A to the claddinglayer P is 1:0-0.05, based on the total weight of the multicrystalparticles A.
 6. The cathode material of claim 5, wherein the claddinglayer P is provided by conductive graphite and/or conductive polymer;and/or, the conductive polymer is at least one selected from the groupconsisting of polyaniline, polypyrrole, polythiophene, polyacetylene,poly(paraphenylene sulfide), poly(3,4-ethylenedioxythiophene) andpolyphenylacetylene.
 7. The cathode material of claim 1, wherein a massratio of the multicrystal particles A to the single crystal particles orquasi single crystal particles B in the cathode material is 0.01-9:1. 8.The cathode material of claim 1, wherein an individual particle strengthof the multicrystal particles A in a test of the micro-mechanicaltesting machine is greater than or equal to 50 MPa; a deformationquantity of the multicrystal particles A prior to fracture is within arange D₅₀×(5-25%) of the multicrystal particles A.
 9. The cathodematerial of claim 1, wherein the cathode material has a powdercompaction density greater than or equal to 3.5 g/cm³ under a pressurecondition of 20 kN; and/or, a specific surface area of the cathodematerial is denoted as A1, the specific surface area of the cathodematerial after a pressure fracturing of 4.5 T is denoted as A2; wherein(A2-A1)/A1 × 100% ≤ 40% .
 10. A method for preparing a cathode materialof claim 1 comprising the following steps: (1) subjecting a transitionmetal precursor Ni_(x1)Co_(y1)Mn_(z1)(OH)₂, lithium salt, and anoptional additive to blending and a first sintering to obtain a firstsintered material; (2) subjecting the first sintered material and anoptional conductive graphite and/or conductive polymer to blending and asecond sintering to obtain multicrystal particles A; (3) subjecting atransition metal precursor Ni_(x2)Co_(y2)Mn_(z2)(OH)₂, lithium salt andan optional additive to blending and a third sintering to obtain singlecrystal particles or quasi single crystal particles B; (4) mixing themulticrystal particles A with the single crystal particles or quasisingle crystal particles B to prepare the cathode material; wherein$\begin{array}{l}{\text{x1+y1+z1=1, 0}\text{.5} \leq \text{x1} \leq \text{1, 0} \leq \text{y1} \leq \text{0}\text{.5, 0} \leq \text{z1} \leq \text{0}\text{.5;}} \\{\text{x2+y2+z2=1, 0}\text{.5} \leq \text{x2} \leq \text{1, 0} \leq \text{y2} \leq \text{0}\text{.5, 0} \leq \text{z2} \leq \text{0}\text{.5,}} \\{\text{-0}\text{.05} \leq \text{x1-x2} \leq \text{0}\text{.05}}\end{array}$ .
 11. The method of claim 10, wherein the additive is atleast one selected from the group consisting of lithium compounds, boroncompounds, tungsten compounds, neodymium compounds, aluminum compounds,zirconium compounds, magnesium compounds and chlorides.
 12. The methodof claim 10, wherein the molar ratio of the transition metal precursorNi_(x1)Co_(y1)Mn_(z1)(OH)₂, the lithium salt and the additive in step(1) is 1:0.99-1.1:0-1; and/or, the first sintering conditions comprise asintering temperature of 650-800° C. and a sintering time of 15-30 h;and/or, the first sintering comprises a temperature rise stage and aconstant temperature stage; a ratio of the temperature rise time tr ofthe temperature rise stage to the constant temperature time tc of theconstant temperature stage satisfies: $\begin{matrix}{0.5 \leq {\text{t}_{\text{r}}/\text{t}_{\text{c}}} \leq 2.5} & \text{­­­(4)}\end{matrix}$ .
 13. The method of claim 10, wherein a mass ratio of thefirst sintered material to the conductive graphite and/or the conductivepolymer in step (2) is 1:0-0.05; and/or, the second sintering conditionscomprise a sintering temperature of 100-400° C. and a sintering time of4-12 h.
 14. The method of claim 10, wherein a molar ratio of thetransition metal precursor Ni_(x2)Co_(y2)Mn_(z2)(OH)₂, the lithium saltand the additive in step (3) is 1: 0.99-1.1: 0-1; and/or, the thirdsintering conditions comprise a sintering temperature of 800-1,000° C.and a sintering time of 15-30 h.
 15. The method of claim 10, wherein amass ratio of the multicrystal particles A to the single crystalparticles or quasi single crystal particles B is 0.01-9:1. 16.(canceled)
 17. (canceled)
 18. A lithium ion battery comprising a cathodeelectrode prepared with the cathode material of claim 1.